A piece of jewelry that is capable of measuring the arousal level -- on a scale of 1 to 20, with 1 being completely asexual and 20 being insatiable -- of its wearer. A related component is also capable of adjusting the arousal level for desired effect. As outlined in the ebook, The Hornometer, by Joe Mudak
Jason wasn't sure if he should make a move on his girlfriend, so he quickly checked the readout on her hornometer. When he saw that it only registered an 8, he quickly raised her arousal level to 15.